GRUBER and COMPAGNO; TAXONOMIC STATUS AND BIOLOGY OF BIGEYE THRESHER 



FIGURE 7.— Jaws of 372 cm TL male Alopias 

 superciliosus (CAS- Ace. 1963-x: 7). Note the 

 elongated, flexed cusps on the anterior and 

 some lateral teeth which are characteristic of 

 males and shown in detail in Figure 10. 

 Photo: L. Compagno. 



Y Yxxxv* *^'^**' 



□ I 



FIGURE 8.— Tooth set from the right side of the jaw of a 278 cm TL female Alopias superciliosus (LJVC-0355). A, anterior teeth; 

 L, lateral teeth; P, posterior teeth. Scale mark at lower right is 1 cm. Photo: L. Compagno. 



bigeye threshers and have documented this sexual 

 heterodonty. Gynandric heterodonty is found in 

 other sharks (see for example Springer 1964; 

 Springer 1966), and in its ordinary form (teeth 

 larger, more erect, and with larger cusps and often 

 less well developed cusplets in males than in 

 females) may aid the male in holding the female 

 during courtship and copulation (Gruber and 

 Myrberg 1977). 



DENTICLES 



Samples of skin from the back below the first 

 dorsal fin were removed from three species of 

 threshers (A. superciliosus, A. pelagicus, and 

 A. vulpinus), dried, and examined under 

 the scanning electron microscope to show the 

 structure of their dermal denticles. The lateral 

 trunk denticles of all three species are similar in 



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